Effects ofAdding Hydrotalcite with Different Compositional Ratios in the Pyrolysis Treatment of Brominated Plastics

In recent years, chemical recycling technologies related to the pyrolysis of plastics into fuels have received increasing attention under the circular economy agenda with respect to resource depletion. Herein, a method is presented to reduce halogen compounds in the product oil derived from the pyrolysis of polystyrene with tetrabromobisphenol A. Analysis was undertaken to identify the bromine compounds present in the residue after the pyrolysis treatment. Pyrolysis was conducted in the presence of hydrotalcites as a function of the Mg and Al additive composition ratio (type 1; KW-1000 and type 2; K W-2000). The bromine compounds identified in the oil after pyrolysis at 400 °C were determined as 2-bromophenol, 4- bromophenol, 2,4-dibromophenol, 1- bromomethylbenzene, 2- bromomethylbenzene, and 3,6-dibromo-2,5-xylidine. In the absence of hydrotalcite, bromine compounds were still detected in the product oil, residue and gas, whereas the addition of KW-2000 reduced the concentration of bromine compounds in the product oil. The reduced concentration of the bromine compounds in the product oil is suggested to be related to the trapping of bromine by the added hydrotalcite during the pyrolysis of the plastic.